Most Helpful Girl
Yeah I think your last sentence is the best way to go. Don't delay the situation. Don't even wait until you see him next if it's not going to be tomorrow or later today/tonight. I would just go on an do it right now if you can. I don't believe in putting something like this off. There's never a good time to break up with someone or even a good way. Maybe a better way but not the best way (if that makes sense).
Definitely don't even push the friend thing (I honestly wouldn't even mention it). That's just upsetting. Be honest and very clear but don't be brutal. Just tell him exactly how you feel and let him know things are definitely over.